I need help with my assignment

Hi
I have a question...as I couldn't find the answer in any grammar book...

Why is in this sentence used "as saying"?

The story quoted Ranier Kuhne of the University of Dortmund in Germany as saying:"Plato wrote....

and why is there a difference in capitalising of the word : e/Earth

...some consisting of Earth and the others of water...
and
...there were violent earthquakes and in a single day and night all sank into the earth and the island of Atlantis in like manner dissapeared into the depths of the sea...